Abstract
Purpose :
The Useful Field of View test (UFOV) measures the speed of higher-order processing of visual sensory information, and is an indicator of “functional” vision, such as accident risk in older drivers. Cognitive tasks involving selective attention (ignoring distracters) are impaired early in dementia. The most complex part of the UFOV test is the selective attention (SA) component, which generates a quantitative trait (processing time in milliseconds). The aim of this study was to explore the association between SA and cognitive and visual parameters and establish the extent of SA variation that can be attributed to genetic factors.
Methods :
370 TwinsUK cohort participants (mean age=57.9 years; range 18-90) (86.3% female, 94% British Caucasian) undertook the UFOV test, alongside cognitive tests (Mini Mental State Exam (MMSE), verbal fluency (VF) and national adult reading test (NART)) and ophthalmologic examinations, including OCT and contrast sensitivity. Associations between SA and age, sex, ethnicity and RNFL thickness, were assessed using uni- and multivariable linear regression models, adjusting for family structure. Associations between SA and MMSE and VF were assessed using ANOVA and MANOVA in one twin per pair (n=180). Heritability of SA was calculated using maximum likelihood structural equation modeling in 91 monozygotic and 60 dizygotic twin pairs.
Results :
Overall, SA was strongly associated with age (β=0.03, p<1x10-4) but not with sex or ethnicity (p>0.05). SA was associated with contrast sensitivity, independent of age (β=-0.62, p=0.01). Furthermore, SA was found to be strongly associated with MMSE, F(15,486)=3.1, p=1x10-4, independent of age and contrast sensitivity but not with VF or estimated NART verbal IQ (p>0.05). Longer SA time was associated with thinner average RNFL (β=-3.07, p=0.03), but this was not independent of age. Heritability of SA was estimated to be 15% (95%, CI=0-59%).
Conclusions :
This study found that the ‘Selective Attention’ component of the UFOV test is associated with MMSE score, but not with verbal cognitive tests. The lack of association with RNFL (unlike MMSE) suggests that SA reflects loss of higher-order visual processing that is not mediated through loss of ganglion cells (or, by extension, cortical volume). Genetic factors only explain a small proportion of SA variance, suggesting environmental factors account for most.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.